Evaluation of Isometric Shoulder Muscle Contraction during Awakening after Arthroscopic Rotator Cuff Repair / 대한스포츠의학회지

ABSTRACT

Purpose@#Most rotator cuff repairs are performed under general anesthesia, and the shoulder muscles undergo exertion during the patient’s awakening. These may lead to subsequent retear. The purpose of this study is to evaluate the characteristics of shoulder muscle contraction during awakening from general anesthesia after rotator cuff repair. @*Methods@#Twenty patients underwent arthroscopic rotator cuff repair. Surface electromyography was used to investigate the amplitude of shoulder (upper trapezius [UT] and biceps brachii [BB]) and body (rectus femoris, RF) muscles during awakening in the operating room and resting in the postanesthesia care unit (PACU). @*Results@#The mean maximum voluntary isometric contraction (MVIC) of the UT, BB, and RF during awakening were 28.00%, 27.84%, and 35.65%, and the mean durations of activation were 3.98, 2.50, and 2.71 seconds. In the PACU, the mean MVIC of the UT, BB, and RF were 27.18%, 25.03%, and 27.20%, and the mean durations were 2.72, 0.26, and 0.67 seconds. No correlation between muscle contraction and postoperative pain was identified. @*Conclusion@#Less than 10% of the involuntary muscle contractions of the UT and BB measured in this study exceeded 20% of the MVIC and the contractions lasted less than 4 seconds. As the percentage of the MVIC of the rotator cuff is typically lower than that of the UT and BB, strong contractions of the rotator cuff muscle with detrimental effects occur at a low frequency and short duration. Therefore, retear due to muscle contraction during awakening is unlikely.